| Keck mid-infrared imaging of circumstellar debris disks around the pre-main sequence stars, beta Pictoris, HR. 4796A and 49 Cet are presented. It is demonstrated that high resolution thermal imaging at mid-infrared wavelengths is the preferred method to resolve the inner regions of circumstellar disks, because of little contamination by the photosphere in this frequency regime. Our maps of the dust morphology reveal features like sharp ring confinement, asymmetric disk brightness, and in the case of beta Pictoris, a multitude of rings with different orbital inclinations. These features join others found in a small but growing number of debris disk discoveries by direct imaging. Taken together, these present a mounting evidence of planetary signatures around pre-main sequence stars. As a first step to understanding star and planet formation in the conditions of specific molecular clouds, the Spitzer Space Telescope photometric measurements of the Chamaeleon II dark clouds are surveyed for young stars with cicumstellar disks. Twenty one new pre-main sequence stars are discovered in the Chamaeleon II dark clouds, identified by Spitzer photometry. |
